There has been a demand for the decrease in the developing time in relation to the silver halide photographic light-sensitive material, thus the demand for the development of light-sensitive materials ensuring the more rapid treatment.
It is known that a light-sensitive material comprising silver halide grains involving larger silver chloride content can enabling the rapid developing processing, and that such a material shows a considerably high developing speed under a specific condition, wherein, for example, no bromide content is allowed in the material.
However, though a light-sensitive material having silver halide grains involving a larger silver chloride content is suitable for the rapid treatment, its sensitivity is disadvantageously low. This disadvantage arises from a characteristic of silver shloride; it only absorbs little, if any, visible light. To solve this disadvantage, a variety of sensitizing means are required. The chemical sensitization of grains involving a high silver chloride content readily causes fogging, and when raw samples (raw samples prior to exposure) are stored for a longer period, the fogging may increase, thus deteriorating the sensitivity.
At the same time, an anti-fogging agent is usually added into a silver halide emulsion to prevent the fogging. Such an anti-fogging agent usually deteriorates the sensitivity of the emulsion, therefore, it is disadvantageous to incorporate an anti-fogging agent, as mentioned above, into an emulsion possessing high silver chloride content and being inherently low in the sensitivity. Therefore, when using an anti-fogging agent, it is mandatory to provide the emulsion with the effective sensitization means. However, it is the reality that the incorporation of an anti-fogging agent into an emulsion possessing a high silver chloride content makes the sensitization means less effective. Particularly, when a conventionally known fogging restrainer such as tetrazaindene or mercapto compound which is readily adsorbed onto silver halide grains is used, the sensitizing dye is desorbed by such a compound, deteriorating the sensitization effect, even if the grains have been sensitized with the sensitizing dye. This tendency is especially significant with an emulsion having a high silver chloride content.
To solve this dilemma, it is theoretically possible to develop either a sensitizing agent exerting an effective sensitizing power upon an emulsion possessing a high silver chloride content and the sensitizing effect thereof is not lost by any fogging restrainers, or to develop a fogging restrainer being capable of exerting effective anti-fogging power upon an emulsion possessing a high silver chloride content, and having no adverse effects upon any sentitizing function. However, it is extremely difficult to realize such a sensitizing agent or a fogging restrainer. Accordingly, there is no alternative but to discover the combination of a sensitizing agent and a fogging restrainer each of which being capable of fully attaining the function thereof without exerting an adverse effect on the counterpart. However, there are diverse varieties of compounds known as sensitizing agents, even when the application is limited only to those for an emulsion having a high silver chloride content, and at the same time, there are various fogging restrainers. Therefore, it has been extremely difficult to discover the combination of a sensitizing agent and a fogging restrainer each of which being capable of fully achieving the advantage thereof as well as compensating the disadvantages of the counterpart.
At the end of continued and devoting studies, the inventors have successfully discovered that the satisfactory sensitization is achieved by incorporating a certain spectral sensitizing dye into an emulsion having a high silver chloride content, and simultaneously, by using a certain mercapto compound as a fogging restrainer, and that, accordingly, the fogging is satisfactorily inhibited without reducing the effect of the sensitization.